US2623774A - Magnetic article grip for toy hoists - Google Patents

Description

Dec. 30, 1952 H. c. HUBBARD 2,623,774

MAGNETIC ARTICLE GRIP FOR TOY HOISTS Filed Jan. 26. 1950 INVENTOR.

Afforney Patented Dec. 30, 1952 UNITED STATES PATENT OFFICE MAGNETIC ARTICLE GRIP FOR TOY HOISTS Harold C. Hubbard, Lansing, Mich.

Application January 26, 1950, Serial No. 140,607

6 Claims.

This invention relates to toys and more particularly to an improved magnetic grip for a toy crane.

The desirable objective in designing a toy is providing a unit of simple, economical construction but of a dynamic rather than static character. Toy cranes capable of grasping an object and raising it have the desired characteristic of being dynamic. Many types of grips have been designed for these cranes, among them magnetic grips. However, these grips have been complicated, complex to operate and relatively expensive to fabricate. I have observed that children playing with toy cranes have a fairly constant pattern of operation. When the beam of the crane is made adjustable in height they seldom, if ever, use the beam except at its upper limit of travel. Therefore, it is unnecessary to design the crane with a beam of adjustable elevation. I have also observed that they prefer to play with toys operated by means of a single control such as a crank or lever. The use of two or more controls tends to confuse them. Thus, it is desirable to combine the controls for all of the moving parts of the toy into a single unit. It is also preferable to design the toy to appear and operate in a fashion as nearly as possible simulating the full scale machine from which it is copied.

Existing toy cranes employing a magnetic grip have failed to provide the desired combination outlined above. They fail to solve the problem of discharging the object held by the magnet by means of a simple, inexpensive mechanism. Since temporary magnets require a source of electrical power and a switch to control them, they are too expensive for the average toy. Therefore, permanent magnets have been employed with the load discharged by withdrawing the magnet from. the load. To accomplish this, the magnet is surrounded by a non-magnetic frame against which the load is drawn by the magnet. To release the load, the magnet is moved away from the load while restraining the load from following by means of the frame. However, since this principle involves the relative separation of two suspended parts, it has been common practice, until my invention, to firmly secure the frame to some stable support. .Thus, existing magnetic grips employ a frame or shell securely mounted to the end of the crane beam whereby it was necessary to lower the entire beam in order to bring the magnet in contact with the article to be picked up. This required two separate controls. One control regulated the elevation of the beam and the other control theo peratlon of the magnetic grip. The resulting structure failed to simulate a standard crane either in appearance or operation. Further, it required anexcessive number of parts and lacked the desired simplicity of operation to appeal to children.

My invention solves this problem by suspending the magnetic grip from a flexible cable whereby the grip is vertically movable independently of the beam. The flexible cable is capable of both elevating the grip and causing the grip to release the load. Thus, by means of my invention, the single control for raising and lowering the magnetic grip also functions to release the load held by the grip.

It is, therefore, a primary object of my invention to provide a toy crane having a magnetic article grip vertically movable independently of the cranes beam.

It is a further object of my invention t provide a toy crane having a magnetic article grip in which the grip is so designed that the articles may be discharged from it by means of the same cable by which the magnetic grip is suspended.

It is an additional object of my invention to provide a toy crane having a magnetic article grip in which all of the controls are combined in a single lever and adapted to economical manufacture.

These and other objects of my invention will be immediately seen by those acquainted with the design and manufacture of toys upon reading the following specification and the accompanying drawings.

In the drawings:

Figure 1 is a side elevation view of a toy crane equipped with my improved magnetic article grip.

Figure 2 is an enlarged fragmentary plan view of the free end of the beam of the toy crane.

Figure 3 is a sectional elevation view of the free end. of the crane beam and of my improved magnetic article grip taken along the plane III--III of Figure 2 showing the unsectioned magnet in operating position.

Figure 4 is a sectional elevation view of the free end of the toy crane and my improved magnetic article grip taken along the same plane as Figure 3 but showing the magnet in discharge position.

Figure 5 is a fragmentary sectional elevation view of the cable passagethrough the body structure of the toy crane.

Figure 6 is a sectional plan view of a modified design for my improved toy magnetic article grip.

Figure 7 is a fragmentary side elevational view of a further modified design for my improved toy magnetic article grip; In executing the objects and purposes of my invention I have provided a toy crane having a beam of fixed elevation supporting a flexible cable having a magnetic grip suspended on its free end. The magnetic grip consists of a magnetvertically adjustable within a housing and having a collar for contacting the beam of the crane whereby the magnet may be moved up-'- wardly relative to. the housing for discharging its load.

In the following description th terms forwardly and rearwardly are frequently used and are to be taken as meaning forwardly in l the direction of the free end of the beam of the crane and rearwardly away therefrom. The terms upwardly and downwardly are also frequently used and are to be taken as upwardly in the direction in which the crane is normally used and as shown in Figure 1 and downwardly away therefrom.-

Referringnow to the drawings in greater detail, the numeral l indicates a crane having a housing 2 pivotally mounted on a base 3. The base 3 is supported by any convenient means such as the wheels 4. At the forward end of the housing 2 an elongated beam 5 is fixedly mounted to the housing 2. Thebearn 5 extends away from the housing 2 in an upwardly and forwardly direction. I 4 v g A crank 6 is mounted on the housing 2. The

crank 6 extends across the entire width of the 7 housing 2 whereby it may be jo'urnalled in each side of the housing 2. whereby the crankB may be locked against rotation in ither direction.- Midway between the sides of the housing 2 an opening is provided through the upper portion of the forward face of the hens-rig 2. The opening is surrounded by an eyelet or grommet 1 (Fig.5).

Adjacent the free end of the beam 5, the beam is equipped with a tab 8 extending substantially horizontally when thebe'arn 5' is in its inclined position. The horizontal; position of the tab 8 facilitates jr'narlipuiation of the hereinafter described magnetic grip H. An opening passes centrally through the tab 8 and is surrounded by a g'rcrnmet 9. A flexible cable lil'having its freeend depending below the tab 8 passes through th grommet 9, along the beam 5 and through the grommet I. The end or the flexible cable 10 within th housing 2 is anchored to the crank 6 whereby rotation of the crank 6 in one direction will wind the cable l4] upon the crank and rotation of the crank 6 in the opposite direction will unwind the cable from the crank.

At the free end of the cable it, below the tab 8, a magnetic grip H is mounted on the cable 10. The magnetic grip H consists of a nonmagnetic, tubular housing [2 having a closed lower end it. The upper or open end of the housing i2 is closed by means of 'a nonmagnetic plug I of substantial thickness. Apassageway I 5 passes upwardly through the center of the plug Ml. On

the upper side ofthe plug M an elongated tubular collar I6 is mounted concentrically with the passageway in the plug I l. The cable It extends throug'hthe tubular collar l6 and the passageway l5 and interiorly of the housing I2 is attached to a permanent magnet I? slidably seated within the housing [2. The length of the housing [2 relative to the magnet I? is such that the magnet is free to move longitudinally of the housing it a substantial portion of the Means are provided 4 housings length, such as a third or half. As will appear mor fully hereinafter, the length of permissible travel of the magnet il' within the housing 52 is of substantial importance to my invention.

The various parts making up the beam 5, base 3 and housing 2 and the crank i may be made of any suitable material, such as wood, sheet steel or aluminum. The materials, however, used for the magnetic grip H are important. The housing l2 must be made of a material, such as aluminum or plastic, which is nonmagnetic whereby it will not be attracted to the magnet il The plug it must also be of a nonmagnetic material whereby there will be no magnetic attraction b tween the plug M and the magnet ll when the magnet is in raised position. Unless this is true the housing will not move freely relative to the magnet. It is also essential that the housing be mad of a material having a thin Wall which will not seriously impair the magnetic field, particularly when the magnet is used to draw an article tightly against the lower end is of the housing l2. It is also desirable that the total weight of the housing E2, the plug i i and the collar It be small, thus reducing the proportion of magnetic energy necessary to ma ntain the housing in its raised position relative to th magnet when the magnet is supporting an article drawn tightly against the lower ene- Iil of the housing [-2. The magnet itself is made of a material suitable for permanent magnets, such as a nickel or cobalt alloy.

The operation of my toy is extremely simple. The crank 6 is turned in such a manner that the cable It is unwound, thuslowe'ring the magnetic grip l 5. When the magnetic grip i l is not operating, the magnet I1 is normally at the upper limit of its travel within the housing l2. This results from a downward travel of the free nousing l2 under the influence of gravity. As the crank 6' is rotated in: such a fashion as to unwind the cable It, the magnetic grip ii is lowered. When the magnetic grip l i approaches an article attracted by the magnet, the housing l2 will strike the article, and continued release of the cable is will permit the magnet under its own weight to move towardthe article. As the distance between the, article and the magnet decreases the magnet will be drawn toward the article, thus moving the magnet toward'the lower end of the housing I 2. If the article is light, the magnet will attract the article toward it, thus the article will force the housing l2 upwardly about the magnet until contact is made between the magnet l"! and the lower end 13 of the housing 12.

Once the magnet has gripped the article, the direction in which the crank 6 is rotated may. be reversed, withdrawing the cable and raising the magnetic grip. Under the influence of the magnet I? the article indicated by the numeral it will be lifted by the magnet. Themagnet will continue to hold the article until the collar It strikes the grommet 9 in the tab 8'. Uponcontact between the grommet 9 and the collar It, further upward movement of the housing I'! is prevented. However, since the cable is attached to the magnet il only and is free to move relatively to the housing 12, continued withdrawal'of the cable is wil1 pull the magnet upwardly relativeto the housing 12. Since the article It is held against further upward movement. by the lower end. It of the housing I 2, the continued upwardlymova' ment of the magnet I"! will separatethe magnet from the article. By the time the magnet I! has reached the upper limit of its travel within the housing I2, the influence of the magnet I! over the article I8 will become so weak that the article will fall from the magnetic grip under the force of gravity. These ends may be accomplished since the force with which a magnet and an article having paramagnetic characteristics are attracted is directly proportional to the strength of the poles and inversely proportional to the square of the distance between them. Thus, the length of travel of the magnet within the housing that is necessary to permit the magnet in one position to effectively grip the article and in another position to release the article is dependent upon the strength of the magnet. However, due to the rapid decrease of the force of attraction between a magnet and a paramagnetic article as the magnet and article are separated, this distance for the average magnet need not be very great. Therefore, it is the length of the housing which is critical in providing a magnetic grip of this type capable of efiiciently attracting and discharging paramagnetic articles.

The collar It serves as a bumper and travel limit for the housing I2. It is possible to eliminate the collar and permit the plug M to contact the beam for effecting the same purpose. However, the collar spaces the magnetic grip from the beam at the time of discharge of the article It, thus giving the entire crane a more realistic appearance. In addition, inasmuch as the beam 5 is normally inclined, unless there is provided some contacting means, such as the collar and tab, normal to the direction of travel of the magnetic grip I I, the magnetic grip will be forced into an inclined position upon contacting the beam 5. This is not desirable both from the appearance standpoint and the resulting strain on the cable Hi. It is seen from this description of my invention that the single operation of winding and unwinding the cable It affects not only the raising and lowering of the articles supported by the magnetic grip II but also effectively control the discharge of the magnetic grip when such is desired.

When small, light objects such as pins or paper clips, are picked up by the magnetic grip ll, some of these objects may cling to the side of the grip as well as to the end of it. Sometimes these objects climb the side of the housing l2 following the magnet I! as it Withdraws upwardly in the housing. This results in a failure to properly discharge these objects since the field of the magnet never becomes sufliciently spaced from the objects. This condition may be eliminated in several ways including providing a housing having thick side walls and a thin end or bottom member. The same result may be obtained by providing thin side walls and equipping them with internal ribs to space the magnet substantially from the side walls. In both of these constructions the design effects a greater spacing between the magnet and the objects in the side wall areas of the housing, thus, weakening the magnetic field in this area. The tendency of the smaller objects to cling to the side wall of the housing will be reduced but not entirely eliminated. However, the magnetic field will not be strong enough to cause them to follow the magnet up the housing. Thus, they will be discharged when the magnet is withdrawn.

The construction utilizing the internal ribs is illustrated in Figure 6 wherein a thin walled housing 12a of larger external diameter than the 6 housing I 2 is used. The magnet I1 is cradled between the internally extending ribs 30, thus, spacing the magnet substantially from the external surface of the housing 12a.

Another construction suitable for preventing small objects from following the mgnet I! in its upward travel within the housing I2 is shown in Figure '7. The housing l2 at its lower end is equipped with a radially extending flange or ring 46 of nonmagnetic material. The ring 40 extends radially outwardly from the housing I2 a suificient distance that at its periphery the magnetic field is too weak to attract any of the objects. The use of the ring not only prevents incomplete discharge of smallobjects but entirely prevents them from becoming attached to the side of the magnetic grip." The ring 410 may be a separate ring of the same or different material as the housing I2 and attached to the housing in any suitable manner. It may be made integral with the housing l2 or it may be simply a radial extension of the lower end member of the housing. The selection of one of these constructions is dependent upon the particular fabricating problems involved.

Numerous other modifications of my invention may be made without departing from the principle of my invention and each of these modifications is to be considered as included in the hereinafter appended claims unless these claims by their language expressly provide otherwise.

I claim:

1. In a toy crane for lifting magnetically attracted articles, said toy crane having a beam including a free end extending outwardly therefrom, a rotatable crank and a cable having one of its ends attached to said crank and the other of its ends depending from said free end of said beam, the improvement in said crane comprising: a nonmagnetic, elongated, hollow housing open at one of its ends and closed at the other of its ends; a nonmagnetic plug for closing said open end of said housing; the walls of said plug defining a central aperture therethrough for slidably receiving said cable; a permanent magnet slidably mounted within said housing, said magnet having a length substantially less than the spacing between said plug and said closed end of said housing; said magnet abutting said closed end of said housing when said magnet is supporting an article; means for attaching said depending end of said cable to said magnet whereby as said cable is moved toward said free end of said beam and said magnet is supporting an article movement of said housing will be stopped by said beam and continued movement of said cable will urge said magnet toward said plug for reducing the strength of the magnetic field at said closed end of said housing and releasing said article.

2. A toy crane as described in claim 1 wherein an annular collar is mounted on said plug concentrically with said aperture, said collar extending from said plug in a direction away from said housing whereby said collar will contact said free end of said beam for limiting travel of said housing in one direction.

3. In a toy hoist comprising: a cable vertically. reciprocably movable parallel to its axis; an article gripping magnetic element mounted on one end of said cable; a nonmagnetic, vertically elongated, hollow housing having an upper end and a lower end; said housing slidably mounted on said magnetic element and supported thereby; said magnetic element, in article holding position, seated at said lower end of said housin a stop fixedly positioned in relation to said cable for slidably receiving said cable exterioi'ly of said housing; said housing movable with said magnetic element and said cable whereby said cable, when travelling upwardly, will move said housing to cause said upper end of said housing to contact said stop and continued upward movement of said cable will move said magnetic element longitudinally of said housing for repositioningthe magnetic field of said magnetic element away from said lower endof said housing.

4. A toy h ist as d scr d i c im 3 wher said housing is equipped with a plurality of ina l x end n ib o on ac n sai masnetic l m w ereb aid ma e ic m nt is spaced from the inner wall of said housing.

5. A toy hoist as described in claim 3 wherein said housing is equipped with a radially outwardly extending, nonmagnetic flange at said lower end whereby said article may not follow said magnet up said housing as said magnet; is moved toward said upper end of said housing.

6. In a toy hoist, a magnetic grip for supporting an article, the improvement in said magnetic grip comprising: a cable of adjustable length; a magnet supported on the end of said cable; an elongated, nonmagnetic housing having end walls and defining a central chamber for slidably receivin'g said magnet; one of said end Walls of said housin'g'defining an aperture for receivin said cable; said one end Wall of said housing normally resting upon said magnet for supporting Said housing; a fixed stop surrounding said cable ex teriorly of said housing, said cable freely movable through said stop; said magnet, in article supporting position, seatedat the end of said housing remote from said aperturewith said housing sup ported by the article; whereby as said cable is moved toward said stop, movement oi said housing with said cable will be halted upon contact between said stop and said housing and continued movi of s d ab e wi l u e sai asnet away from said article for rele sing said article. V

QL D HUBBARD- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 25 Number Name Date 1,685,767 Keedy Sept. 25, 1928 2,417,762 Koller Mar. 18, 1947 2,539,435 Kirby Jan. 20, 1951

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